Infinitely variable cone pulley transmission

ABSTRACT

A fully hydraulic control mechanism for an infinitely variable cone pulley transmission in which the axially movable conical disc of each pulley is pressed against an endless belt or chain running between the pulleys with a different contact pressure than the corresponding disc of the other pulley. The control mechanism acts at the same time upon the axially movable discs on the driving and driven shafts of the transmission, and the contact pressure of all discs is load-responsive as well as speed-ratio progressive.

United States Patent Inventors Otto Dittrich;

Herbert Kirchner. bad Homburg Vor Der Hohe, Germany Appl. No. 887,048Filed Dec. 22, I969 Patented Aug. 3, 1971 Assignee Reimers Getriebe A.G.

Zug, Switzerland Priority Dec. 24, 1968 Germany P 18 16 949.8

INFINITELY VARIABLE CONE PULLEY TRANSMISSION 14 Claims, 12 Drawing Figs.

U.S. Cl ..74/230.17F. 74/230. 17 (M), 74/865 Int. Cl ..Fl6h 55/22, 860k21/10 Field of Search 74/865,

[56] References Cited UNITED STATES PATENTS 3,052,132 9/1962 Dittrich etal 74/230.17 (F) 3,395,586 8/1968 Kirchner 74/230.l7 (F) 3,368,4262/1968 Karig et a1. 44/865 Primary Examiner-Leonard l-l. GerinAttorney-Jennings Bailey, Jr.

ABSTRACT: A fully hydraulic control mechanism for an infinitely variablecone pulley transmission in which the axially movable conical disc ofeach pulley is pressed against an endless belt or chain running betweenthe pulleys with a different contact pressure than the correspondingdisc of the other pulley. The control mechanism acts at the same timeupon the axially movable discs on the driving and driven shafts of thetransmission, and the contact pressure of all discs is load-responsiveas well as speed-ratio progressive.

PATENTEDius 3:971 3,596,528

SHEET 1 OF 5 INVENTORS OTTO DITTRICH HERBERT l HNEF? BY K RC %LLKLLLL6F)PMENTEU AUG BIS?! 3 596, 528

INVENTORS OTTO (TTRICH HERBERT CHNEK PATENTEUAUG anew 3.596.528

SHEET w 0F 5 IMFENTORS OTTO, D'ITJRICH HER BERT KUECHN BY ERINlFINl'lIilElLY VARIABLE (NONE lPlUlLlLElK TRANSMISSION BACKGROUND OFTHE INVENTION 1, Field of the Invention The present invention relates toan infinitely variable cone pulley transmission which comprisesassociated pairs of conical disks on the driving and drive sides ofthetransmission, and an endless transmitting element such as a belt orchain running between the two pairs ofconical disks. One disk ofeachpair is slidable in the axial direction on its shaft relative to theother disk and is designed so as to form a rotatable hydraulic cylindercontaining a piston which is rigidly connected to this shaft. Theseconical disks at both sides of the transmission are pressed against thetransmitting element with contact pressures which solely depend upon thehydraulic pressure in the cylinders which is produced automatically in amanner so as to be directly responsive to the load which is exerted uponthe transmission. This transmission further comprises a control elementfor maintaining and varying the speed ratio of the transmission, and adistributing slide valve which is acted upon by the control element andadapted to receive a pressure fluid such as oil from a suitable sourceunder pressure and to distribute this pressure fluid to the hydrauliccylinders.

2. The Prior Art In a transmission of this known type, as disclosed bythe US. Patent No. 3,45 l ,283 and the copending British application No.36,680/67, the slide valve is provided with four control edges and thecontrol element consists of a control lever which is pivotably connectedto the slide valve and permits the latter to be arbitrarily adjusted,for example, by hand for varying the speed ratio of the transmission andalso to be adjusted by one of the axially slidable conical disks inproportion to the distance of its axial movements. For this purpose, oneend of the control lever is connected to an actuating element foreffecting the manual adjustments, while its other end engages into aperipheral groove in the outer surface of the axially slidable conicaldisk.

While such a control element is very suitable especially when the driveunit is of a type which rotates at a constant speed or when thetransmission should always run at a certain speed ratio, it is advisableto employ a control element ofa different construction if the poweroutput and the speed of the drive unit, for example, a carburetorengine, are variable. Such a control element as disclosed, for example,by the French Patent No. 1,425,189 in connection with an infinitelyvariable cone pulley transmission in which the contact pressures of theconical disks at the driving and driven sides of the transmission areproduced solely by mechanical means, con sists of an output controllever for the drive unit which acts upon a governor which determines thespeed ratio of the transmission and is, in turn, controlled by thevariable driving speed ofthe drive unit.

A transmission of the type as first described above is further providedwith a control biasing driven side which is inserted into the returnline of the pressure fluid which flows through this line under thehydraulic pressure prevailing at the driven side of the transmission.The initial tension of this biasing valve is variable in response to thehydraulic pressure prevailing at the driving side of the transmission.lfin such a transmission the load is increased, for example, on itsdriven side, this has the effect, in view of the general law of suchtransmissions, that the transmitting element always exerts a greaterspreading force upon the driving disks than upon the driven disks, thatthe conical disk which is axially slidable at the driven side yieldsunder the spreading force of the transmitting element because thehydraulically produced contact pressure of this disk against thetransmitting element is insufficient to balance this spreading force. Atthe same time, the axially slidable conical disk at the driven side ofthe transmission moves in the direction toward the transmitting elementand the speed ratio of the transmission is therefore changed so that itsdriven shaft will run at a lower speed. This operation has the resultthat by the action of the control lever and the slide valve with fourcontrol edges which is pivotably connected thereto the hydraulicpressure will be increased at the driving side of the transmission. Thisincreased hydraulic pressure at the driving side further causes by meansof the biasing valve an increase of the hydraulic pressure at the drivenside and thus at the same time an increase of the pressure ratio at bothsides of the transmission. This transient pressure variation comes to astop when the slide valve is in a position in which in operativeassociation with the biasing valve the contact pressures which areexerted by the two pairs of conical disks upon the transmitting elementare in a state of balance with the spreading forces which are exerted bythe transmitting element upon these disks.

These adjusting operations proceed, however, in the reverse directionwhen the load upon the driven side of the transmission decreases andthus also the torque which is to be transmitted by the transmission. Allof these adjusting proceedings have, however, in common that an increaseor decrease of the hydraulic pressure at the driven side of thetransmission by means of the biasing valve can always occur only when acorresponding increase or decrease of the hydraulic pressure has alreadyoccurred at the driving side as the result of the adjustment of theslide valve. Stated in different words, this means that a variation ofthe torque which is conducted through the transmission cannotsimultaneously exert any influence upon the height of the hydraulicpressure at the driving and driven sides of the transmission so as toeffect a very quick adjustment of the latter to the new load conditions.This leads to a certain sluggishness of the known types of hydrauliccontactpressure producing systems which is especially of disadvantage ifthe changes in the torque occur frequently of in quick succession.

It is further one of the laws of infinitely variable cone pulleytransmissions that the ratio between the contact pressures on thedriving and driven sides of such a transmission changes within certainlimits in response to the particular load upon the transmission and tothe particular speed ratio thereof. If, for example, the driving speedof the drive unit is constant and a certain power is to be transmittedby the transmission, this change has the effect that at a variation ofthe speed ratio of the transmission the ratio of the spreading forcedecreases which is exerted by the transmitting element upon the conicaldisks at the driving and driven sides so that the driven shaft of thetransmission increases in speed.

Therefore, as disclosed, for example, by the German Patent No. 1,08 l,733, the known transmissions in which the contact pressures areproduced at least partly mechanically have been provided with a numberof very complicated mechanical pressure-producing means for producingcontact pressures which are not only responsive to the load upon thetransmission but also to the particular speed ratio thereof. However,for transmissions of the type as referred to at the beginning, in whichthe contact pressures of the conical disks upon the transmitting elementare produced only hydraulically, there has so far been no disclosure ofany possibility which would permit the ratio between the contactpressures on the driving and driven sides of the transmission to be alsoresponsive to a change of its speed ratio. Although in most cases it issufficient to operate such a transmission with contact pressures whichare merely dependent upon the particular load acting upon thetransmission, very high-grade transmissions, for example, motor vehicletransmissions, which should take up the smal lest possible space and beable to transmit very high powers must be designed so as also to beresponsive to changes in the speed ratio and to insure that at any speedratio the contact pressures of the conical disks upon the endlesstransmitting element will just be high enough so as to prevent thetransmitting element from slipping since such slipping would wear outthe transmitting element and the conical disks very severely and renderthe entire transmission useless very prematurely.

SUMMARY OF THE INVENTION lt is the principal object of the presentinvention to provide an infinitely variable cone pulley transmission inwhich the contact pressures for applying the conical disks of thedriving and driven sides of the transmission against the endlesstransmitting element are produced fully hydraulically, and whichovercomes the disadvantages of this type of transmission as previouslydisclosed. The transmission according to the present invention istherefore to be designed so that the contact pressures of the conicaldisks at the driving and driven sides of the transmission will beproduced and controlled so as to adjust themselves automatically notonly in accordance with the changing loads to which the transmission issubjected but also in accordance with and responsive to the varyingspeed ratio to which the transmission is adjusted. The transmissionaccording to the invention is further to be designed so as to take thefact in consideration that between the lowest and highest speed ratiosto which a transmission of this general type is adjustable, there isalways at least one speed ratio which requires particularly a highcontact pressure of the conical disks upon the transmitting element. ifthe contact pressure would be made of such a strength that at thisparticular speed ratio it would just prevent the transmitting elementfrom slipping relative to the conical disks, this contact pressure wouldbe unnecessarily excessive at the other speed-ratio adjustments. Suchexcessive contact pressures would, of course, mean excessive loads uponthe transmission which would result in undue wear and tear and wouldreduce the useful life of the transmission considerably. It is thereforeanother object of the invention to design the transmission so that thecontact pressures will have the proper strength so as just to preventthe transmitting element from slipping at any speed ratio to which thetransmission is adjustable. A further object of the invention is toproduce and control the hydraulic contact pressures with which theconical disks at the driven side of the transmission are pressed againstthe transmitting element in such a manner that these contact pressureswill no longer be dependent upon the strength of the hydraulic pressureswhich act upon the conical disks at the driving side of thetransmission. Finally, it is an object of the invention to design thetransmission in a manner so as to require much more simple andinexpensive means for attaining the above-mentioned objects than wererequired in previous transmissions in which the contact pressures wereproduced at least partly by mechanical means.

For attaining these objects, the present invention provides aninfinitely variable cone pulley transmission of the type as firstreferred to herein, which, however, is provided on the driving sideand/or on the driven side of the transmission with a pressure controlvalve which is mechanically adjustable by the action of the respectivetorque to be transmitted and also in response to the varying axialpositions of the slidable conical disk and is adapted to determine therequired hydraulic pressure so as to be load-responsive as well asresponsive to the particular speed ratio to which the transmission isadjusted. This pressure control valve may always be acted upon by acompression spring so as to insure that a certain basic pressure willalso be maintained when the transmission is not in operation or notrunning under a load.

One feature of a preferred embodiment of the invention consists inproviding the shaft on which the slidable disk in the form of ahydraulic cylinder is mounted with a bore or channel which extendsthrough the shaft parallel to the axis thereof and leads to thehydraulic cylinder for supplying the pressure fluid thereto, and inproviding the shaft with an additional channel which is connected to thefirst channel which leads to the pressure control valve which is mountedin this shaft, and leads from this pressure control valve to theoutside. Another feature of the invention consists in providing thepressure control valve with a movable intermediate element which bymeans of the compression spring of this valve partly projects radiallytoward the outside of the shaft and presses against an inclined camsurface which extends substantially parallel to the axis of the shaftand is provided in the wall of the bore of the hub of the axiallyslidable conical disk. By means of this inclined surface acting throughthe intermediate element and the compression spring upon the pressurecontrol valve, the latter may be acted upon in response to the load towhich the respective side of the transmission is subjected. For alsoacting upon the pressure control valve in response to the speed ratio towhich the transmission is adjusted, the mentioned inclined surface inthe hub of the slidable conical disk varies in inclination in itslongitudinal direction.

According to a still more preferred embodiment of the invention, inwhich the shaft carrying the slidable disk in the form of a hydrauliccylinder is likewise provided with the mentioned channels and a pressurecontrol valve as described, and in which the intermediate elementlikewise engages upon an inclined surface in the hub of the slidabledisk so that the pressure control valve will be acted upon in responseto the load to which this side of the transmission is subjected, thisinclined surface is provided on a lever which is pivotably mounted in arecess in the wall of the bore of the hub and extending parallel to theaxis of the shaft. This lever engages with a surface of the shaft whichextends parallel to its axis. It is pivotable about a pin which ismounted in a radial bore of the shaft, and is provided with alongitudinal slot into which a pin projects in the radial direction fromthe wall of the hub.

In view of the possible cases in which both of these embodiments of theinvention may be applied, the movable intermediate element may belocated between two of the inclined surfaces both of which extendsubstantially parallel to the axis of the shaft and extend at the sameangle of inclination to a radial plane projecting from the shaft whichintersects the vertex between these two surfaces which extends parallelto the axis of the shaft. These two inclined surfaces between which theintermediate element is located may, however, also be disposed atdifferent angles of inclination to the radial plane which projects fromthe shaft, and the intermediate element preferably consists of a ballwhich engages at one side upon the compression spring which acts uponthe pressure control valve and at the opposite side either with one orthe other or both inclined surfaces depending upon the particularoperating conditions of the transmission.

By means of the different embodiments of the transmission according tothe invention it is'possible to produce the best possible contactpressures at the driving side as well as at the driven side of thetransmission, that is, contact pressures of the conical disks which arejust sufficient to balance the spreading forces which are exerted by thetransmitting element upon these disks and are responsive to theparticular load acting upon the transmission and also to the speed ratioto which the transmission is adjusted at the particular time. By meansof the invention, an excessive contact pressure of the conical disksupon the transmitting element is therefore avoided at any speed ratio towhich the transmission is adjustable, which was impossible in the knowntransmissions in which the contact pressures were produced entirelyhydraulically. Consequently, any of the transmissions according to theinvention will remain properly operative for a much greater length oftime, especially also in cases in which they are used for transmittingvery high powers or are subjected to very high stresses. The meansaccording to the invention for producing hydraulic contact pressureswhich are load-responsive as well as speed-ratio responsive also havethe considerable advantage of being a very simple construction and ofrendering the new transmissions considerably less expensive than theknown transmissions in which the contact pressures were produced bymechanical pressure-producing means so as to be also responsive to thespeed ratio of the transmission.

Finally, the invention has the advantage that the contact pressures atthe driving and driven sides of the transmission may be producedindependently of each other so that it is no longer necessary as inprevious transmissions of this type to wait for a change of the contactpressure of the conical disks at one side of the transmission before anychange of the contact pressure can occur at the other side.

BRIEF DESCRIPTION OF THE DRAWINGS These and additional features andadvantages of the present invention will become further apparent fromthe following detailed description thereof which is to be read withreference to the accompanying drawings which show several embodiments ofthe new infinitely variable cone pulley transmission largely in crosssection and partly diagrammatically simplified. In the drawings,

FIG. I shows a first embodiment of the transmission accord ing to theinvention in which the contact pressures are produced in response to theload upon the transmission and in response to its speed ratio;

FIG. 2 shows an enlarged view of one of the pressure-control valves asshown in FIG. I;

FIG. 3 shows a cross section which is taken along the line lIl-Ill ofFIG. 2;

FIG. d shows a cross section which is taken along the line lV-IV of FIG.6 and shows an enlarged view of a pressure control valve according to amodification of the invention;

FIG. 5 shows a cross section which is taken along the line V-V of FIG.l;

FIG. 6 shows a plan view of one of the elements as shown in FIGS. ll and5;

FIG. 7 shows a slide valve with two control edges;

FIGS. 6 and 9 show a slide valve with four control edges in twodifferent operating positions;

FIG. llll shows another embodiment ofa slide valve with two controledges;

FIG. III shows a second embodiment of the transmission according to theinvention in which the contact pressures are produced in response to theload upon the transmission and in response to its speed ratio; whileFIG. 12 shows a transmission similar to that according to FIG. I, butmodified for its employment in a motor vehicle.

For an easier understanding and comparison of the different embodimentsof the invention, all those parts ofthese embodiments which carry outsimilar functions are designated in the drawings and are referred to inthe following description by the same reference numerals.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The transmission as illustratedin FIG. I is provided with a drive shaft l and a driven shaft 2. Driveshaft 1 carries a pair of conical disks 3 and d and the drive shaft 2 apair of conical disks 5 and 6. These two pairs of conical disks areconnected by an endless transmitting element 7 such as a belt or chain.Disks 3 and 5 are rigidly secured to shafts I and 2, while disks 4 and 6are provided in the form of hydraulic cylinders which are axiallyslidable along the two shafts and relative to their pistons 3 and lwhich are rigidly secured to these shafts so that a pressure chamber IIIis formed between the conical disk 4 and piston ll and another pressurechamber Ill between the conical disk 6 and piston 9. These pressurechambers I0 and 111 may be supplied with oil under pressure through theconduits l2 and I3 so as to produce in these chambers the hydraulicpressures for applying the conical disks 4 and 6 with the requiredcontact pressures against the transmitting element 7.

Conduits l2 and 113 are connected to a distributing slide valve Ml whichdistributes the oil which is supplied thereto by a pump IE to theconduits l2 and 113 in accordance with the particular position to whichthis valve is adjusted. The adjustment of slide valve M may be effectedby a control lever 16 which is pivotably connected thereto and one endof which engages into a peripheral groove 17 in the outer surface of theconical disk 6 for the purpose of maintaining the speed ratio of thetransmission, while the other end of control lever 116 is adjustable bya hand lever I8 for arbitrarily varying the speed ratio of thetransmission.

Conduit I2 is connected with pressure chamber 10 by a bore W in shaft land conduit 13 with pressure chamber 111 by a bore 20 in shaft 2. Eachof these bores l9 and 20 extends substantially parallel to the axis ofshaft I or 2, respectively, and its inner end is connected with anotherchannel 21 or 22 in the respective shaft and with a pressure controlvalve 23m 26, respectively, which is likewise provided in the respectiveshaft l or 2.

FIGS. 2 and 3 show one of these pressure control valves very enlarged soas to reveal its details more clearly. The inner end of each bore 19 and20 forms a throttling passage in which the oil flowing from bore 119 or20 to channel 2i! or 22 in shaft 1 or 2, respectively, may be throttledby the conical end of a valve member 25 which is slidable in. a radialbore 26 of the shaft. Valve member 25 is connected by a compressionspring 27 to a ball 28 which, in turn, engages upon inclined surfaces 29and 30 which extend parallel to the axis of shaft l or 2 in the hub 31of the axially movable conical disk t or 6, respectively. Theseinclining surfaces 29 and 30 may be designed, for example, so as toextend at different angles to the radius of shaft 1 or 2 whichintersects the vertex of these surfaces and the inclination of surfaces29 and 30 also changes in their axial direction. The purpose of theparticular shape of these surfaces 29 and 30 will become clearlyapparent from the subsequent description of the manner of operation ofthe transmission as illustrated in FIG. ll.

Let us assume that shaft l is driven at a constant speed, for example,by an electric motor, and that the transmission is in a state of balancein which the speed ratio to which it is adjusted does not tend tochange. When the transmission is in this condition one-half of thetorque to which shaft I is subjected will be transmitted to thetransmitting element 7 by the conical disk 3 and the other half by ball28 through the conical disk 4. At the other side of the transmission,one-half of the torque will likewise be transmitted to shaft 2 by theconical disk 5 and the other half by the conical disk 28 associated withvalve 22 and ball 6. This torque transmission has the effect thatbecause of the steeper inclined surface 29 in the conical disk 6 on thedriven shaft 2, ball 26 will be pressed into the bore 26 against theaction of spring 27 in accordance with the size of the torque componentwhich is to be transmitted thereby with the result that the flow of oilpassing through bore 20 into the channel 22 will be throttled by valvemember 25 of valve 24 to such an extent that chamber III will containjust the hydraulic pressure which is required for balancing thespreading force which is exerted by the transmitting element 7 upon theconical disks 3 and 41 at the driven side ofth-e transmission.

The inclined surface 30 in the conical disk 6 on the driving shaft l ismade of such an inclination that the throttle valve 23 will always beclosed. Consequently, the hydraulic pressure which acts at the drivingside of the transmission is determined by slide valve M since thetransmission can be in a state of balance only at a speed ratio in whichslide valve 14 in operative association with the control lever 16 andthe setting of the speed ratio by the end of control lever 16 in theperipheral groove 17 supplies pressure chamber 10 at the driving sidewith the hydraulic pressure which is necessary for balancing thespreading force which is exerted by the transmitting element '7 upon theconical disks 3 and 4.

If the speed ratio is to be changed so that the driven shaft 2 will runat a higher speed, this may be effected by pivoting the hand lever lidin the counterclockwise: direction. Slide valve M is thereby shifted soas to supply a higher hydraulic pressure to conduit 12 and thus tochamber It), while the flow of oil into conduit 13 is throttled so thatdisk 4 will be moved toward and disk 6 away from the transmittingelement 7. These movements are stopped when disk 6 taking along thecontrol lever 16 by its peripheral groove 17 has again reversed thearbitrary adjustments of slide valve 14 which was made by means of thehand lever 18 to such an extent that, due to the pressures which arethen supplied to the conduits l2 and 13 in association with thethrottling of the return flow of the oil by means of the pressurecontrol valve 24, the transmission is in a state of balance, that is inthe condition in which the hydraulic pressures which are then containedin chambers 10 and 11 will again just suffice to balance the spreadingforces which are exerted by the transmitting element 7 upon the twopairs of conical disks.

Such a change of the speed ratio of the transmission, however, alsocauses the ratio between the spreading forces to which are exerted uponthe transmitting element 7 at the driving and driven sides of thetransmission would be changed. In order to insure that this fact willalso be considered in generating the hydraulic pressures which arerequired in chambers 10 and 11 for balancing the spreading forces of thetransmitting element 7, the degree of inclination of the surfaces 29 and30 along their axial direction varies in a manner so as to comply withthis law of infinitely variable cone pulley transmissions. This has theresult that the sizes of the contact pressures which are exerted by theconical disks 3 to 6 upon the transmitting element 7 are dependent notonly upon the torque which is to be transmitted at the driving anddriven sides of the transmission, that is, upon the load acting on thetransmission, but also upon the speed ratio position to which thetransmission is adjusted at the particular time. By suitably designingthe inclined surfaces 29 and 30 it is possible to make the contactpressures of such sizes that they will not be excessive on either sideof the transmission. Therefore the contact pressures which are exertedby the conical disks upon the transmitting element 7 will always haveonly just the strength to prevent the transmitting element 7 fromslipping between the conical disks.

If the direction of the torque changes in the transmission asillustrated in FIG. 1, so that shaft 2 becomes the driving shaft andshaft 1 the driven shaft, for example, because the motor which isconnected to shaft 1 is to be operated as a generator, the sizes of thespreading forces which are exerted by the transmitting element 7 uponthe conical disks are also reversed since this element 7 then exerts agreater spreading force upon the conical disks and 6 than upon the disks3 and 4. Such a reversal which also requires a corresponding reversal ofthe hydraulic pressures in chambers 10 and 11 is carried outautomatically by pressure control valves as illustrated in FIGS. 2 and 3since due to the change of the direction of the torque, the inclinedsurfaces which act at the driving and driven sides of the transmissionupon the balls 28 also change so that the less inclined surface 30 nowengages upon ball 28 on shaft 2 and the steeper surface 29 upon the ball28 on shaft 1.

In addition, such a reversal of the direction of the torque also resultsin a small variation of the speed ratio of the transmission becauseslide valve 14 then determines the hydraulic pressure which is containedin chamber 11 which means that, when the transmission is in the balancedcondition, slide valve 14 will be shifted toward the right of itsneutral position. However, because of the very steep characteristic ofslide valve 14, even very small changes of the speed ratio will alreadyresult in strong control impulses so that the variation of the speedratio which occurs at a reversal of the direction of the torque will benegligably small.

When employing pressure control valves with differently inclinedsurfaces 29 and 30, the transmission will therefore operate properlywhen the torque extends in either direction. However, if a change of thedirection of rotation occurs, the contact pressures will no longer havethe proper sizes since the resulting change of the inclined surfaceswhich act upon the balls 28 would then reverse the hydraulic, pressuresrelative to each other which act in chamber 10 and 11 even though shaft1 continues to be the drive shaft and shaft 2 the driven shaft.

It is, however, very easily possible to adapt the pressure controlvalves as shown in FIGS. 2 and 3 to such conditions, that is, to applythem properly to transmissions in which a change of the direction of thetorque and a change in the direction of rotation may be expected. It isfor this purpose only necessary to make both inclined surfaces of eachpressure control valve 23 and 24 at the driving and driven sides of thetransmission of the same inclination relative to the radius of therespective shaft which intersects the vertex between each pair of theseinclined surfaces. The pressure control valve at the driving side of thetransmission then determines the hydraulic pressure which is produced inthe pressure chamber at this side by allowing suitable amounts of oil toflow off, while the pressure control valve at the driven side of thetransmission will be closed so that the hydraulic pressure which iscontained in the pressure chamber at the driven side will be determinedby the slide valve 14.

FIGS. 4 to 6 illustrate another embodiment of the pressure control valveaccording to the invention which is designed so as to carry out the samefunctions as the pressure control valve as previously described. Also,in this case each shaft 1 and 2 is provided with a radial bore 26 inwhich a valve member 25 with a conical tip is slidable which is adaptedto throttle the flow of oil which is supplied through bore 19 or 20 andthen passes into the channel 21 or 22. This throttling effect occurs toan extent which depends upon the force with which ball 28 presses thecompression spring 27 upon the respective valve member 25.

This force is generated by a lever 35 which is inserted into a groove 36which is provided in the wall of the bore in the hub 37 of disk 4 or 6through which shaft 1 or 2 extends, and lever 35 extends substantiallyparallel to the axis of this bore and shaft. One end of this lever 35 ispivotably mounted on a pin 39 which extends radially into the shaft 1 or2, and lever 35 is provided with a longitudinal slot 40 into which a pin41 engages which projects radially inwards from the wall of hub 37. Theother end of lever 35 is provided with two inclined surfaces 42 and 43which may have the same inclination or different inclinations to theradius of shaft 1 or 2 which intersects the vertex between these twoinclined surfaces which hold the ball 28 between them.

If in the transmission as illustrated in FIG. 1 which is provided withthe modified pressure control valves according to FIGS. 4 to 6 a torqueis transmitted between shaft 1 or 2 and the associated hub 37, a smallrelative movement occurs in the peripheral direction between therespective shaft and the associated hub whereby pin 41 pivots the lever35 about pin 39 until one of the inclined surfaces 42 or 43 pressesagainst the valve ball 28 and thereby stops the pivoting movement andalso produces at the same time a radial force upon ball 25 which has asize corresponding to the size of the torque which is to be transmittedbetween shaft 1 or 2 and hub 37. If the surfaces 42 and 43 have the sameangle of inclination, this radial force causes the pressure controlvalve to be closed at the side of the transmission which is then driven,while the pressure control valve at the driving side of the transmissionthrottles the flow of oil from the bore 19 or 20 to the channel 21 or22, respectively, so that the hydraulic pressure in the pressure chamberat the driving side of the transmission will have the strength which isrequired for balancing the spreading force which is exerted by thetransmitting element upon the conical disks of the driving side.Therefore the respective pressure control valve which is in operationproduces load-responsive contact pressures at that side of thetransmission where this valve is located.

The responsiveness of the contact pressures to the speed ratio isattained as the result of the relative axial movement which occursbetween shaft 1 or 2 and the associated flange 37 when the speed ratiochanges. This relative movement causes a change of the leverages betweenpin 39 and pin 41 on the one hand and between the point of engagement ofball 28 with one of the inclined surfaces 42 or 44 and pin 41 on theother hand. This has the result that when a certain torque istransmitted between shaft 1 or 2 and hub 37, different radial forces areexerted upon the valve ball 25 depending upon the relative axialposition of the shaft and hub to each other and that therefore differentradial forces are exerted upon the valve ball 25 depending upon theparticular speed ratio to which the transmission is adjusted. While thepressure control valve at the driven side of the transmission is alsoalways held in the closed position by these different radial forces, theradical forces which change together with the speed ratio produce bymeans of the pressure control valve at the driving side of thetransmission in cooperation with the slide valve Isl a change of thepressure ratio between the contact pressures at the driving and drivensides together with a change of the speed ratio of the transmission. Thedifferent contact pressures which are required at the different speedratios may be structurally attained by making the mentioned leverages ofsuitable sizes.

In the event that a cone pulley transmission according to the inventionshould be capable of producing the best possible contact pressures onlywhen the direction of the torque changes but not also when the directionof rotation changes, the inclined surfaces all and d3 of the pressurecontrol valve according to FIGS. i to a may, of course, be inclined atdifferent angles just like the surfaces 29 and 3th of the pressurecontrol valve according to FIGS. 2 and 3.

The compression spring 27 of the pressure control valve according toFIGS. 12 and 3 or according to FIGS. 4 to b, which should maintain acertain minimum pressure in chambers III and II even when thetransmission is not in operation or is not running under a load so thatthe transmitting element 7 will not have a slack between the two pairsof conical disks 3,4 and 5,6 preferably consists of cup springs whichpermit the stroke of the spring, which occurs when different radialforces are transmitted to the valve member 25, to be made as short aspossible so that the relative movement in the peripheral directionbetween shaft I or 2 and hub 3I or 37, respectively, which is requiredfor producing this radial force may be made as small as possible.

The slide valve I I which is employed in the transmission according toFIG. I is provided with four control edges d7 to 50, and its housing isprovided with a pair of annular chambers 45 and I6. Each of thesechambers I5 and do is associated with one side of the transmission andeach chamber is associated with a control edge M or as, respectively,for controlling the supply of the oil under pressure and with a controledge 49 or 50, respectively, for controlling the return flow of the oil.The control edges d7 and B8 are spaced at such a distance from eachother that, when slide valve M is in its neutral position, the valveports in the valve housing leading to the conduits I2 and I3 are equallyopened. The two outer control edges 49 and 50 are, however, located insuch positions that, when the slide valve is in the mentioned neutralposition, the return flow of the oil toward the return line 57 is shutoff by each of these edges and will not start until the associated innercontrol edge 47 or 45 has shut off the oil supply to the conduit 12 orI3, respectively.

A slide valve ofthis design has the effect that the amounts of oil whichare supplied by the pump I5 can never flow back directly to the returnline 5I via the control edges I7 and I9 or th and 50, respectively. Adirect flow of the oil can always occur only through the pressurecontrol valve 25 or 24 on the driving or driven side of thetransmission. The return flow of the oil from one of the chambers Iii orII via the control edge 49 or 50 after the oil supply has previouslybeen stopped by the control edge 47 or $3 cannot occur until by anactuation of hand lever III a considerable variation ofthe speed ratiohas been effected and thereby also a corresponding variation of thequantities of oil which are contained in the pressure chambers Ill andII.

It is especially of advantage to employ the slide valve 141 in any ofthose cases in which only a relatively small amount of oil can besupplied within a certain period of time by means of the pump I5 or byany other source of oil under pressure so that only a weak current ofoil under pressure can be maintained.

If, however, larger amounts of oil may be supplied within the sameperiod, it is possible to employ a more simple slide valve with twocontrol edges like the slide valve 52 as illustrated in FIG. I in placeof the slid valve Id according to FIG. I. This substitution of the slidevalve will not vary the mode of operation of the transmission accordingto the invention when it is in a balanced position under load. Only ifthe transmission III is adjusted by the hand lever to a speed ratio verydifferent from the previous ratio, this substitution has the result thatone of the conduits 112 or 113 will be closed by the slide valve 55.even though the latter does not permit the return flow of the amount ofoil which is to be discharged from one of the pressure chambers III orII when the speed ratio changes.

In order to permit the amounts of oil which are to be discharged fromone of the pressure chambers to flow back to the oil pump or the likeeven though a slide valve as shown in FIG. '7 is employed, thetransmission as illustrated in FIG. I is to be provided for each of thehydraulic circuits which are supplied with oil through the conduits I2and I3 with an oil outlet opening (not shown) through which therelatively large amounts of oil which were distributed by slide valve 52to the conduits I2 and I3 may flow off continuously. If the speed ratioof the transmission is considerably changed, the amount of oil which isthen to be expelled from one of the pressure chambers may flow offthrough the outlet opening which is associated with this chamber.

FIGS. h and 9 illustrate another embodiment of a slide valve 5d withfour control edges which may be employed for the operation of thetransmission as shown in FIG. I. This slide valve 53 differs from theslide valve M as shown in FIG. 1 merely by the fact that each of theouter control edges 54 and 55 permits the return flow of the oil to thereturn line 5I already before the associate inner control edge 56 or 57has shut off the oil supply. Thus, if slide valve 53 is in thecorresponding position, a part of the amount of oil which is supplied bypump I5 to the hydraulic circuits may 'flow off continuously to thereturn line 5I.

The slide valve 53 with four control edges as shown in FIGS. 8 and 9 istherefore especially suitable for being employed in an infinitelyvariable cone pulley transmission for the operation of which largeramounts of oil under pressure are available and which is designed fortransmitting power in both directions of the torque and in bothdirections of rotation, that is, a transmission in which the pressurecontrol valve of the side of the transmission which is then the drivingside is more or less opened. When such a transmission is in a balanceposition, slide valve 53 will be in the position as shown in FIG. 9,provided the conduit I2 then leads to the driving side and conduit I3 tothe driven side of the transmission. One part of the oil which issupplied by the pump I5 then flows through conduit I2. and the pressurecontrol valve of the driving side which produces the hydraulic contactpressure which is required at that side, while the other part of the oilwhich is supplied by pump I5 flows off to the return line 51 via thecontrol edges 57 and 55 which also determine the hydraulic pressurewhich is required at the driven side of the transmission. Since acurrent of oil under pressure flows continuously both at the drivingside of the transmission through the pressure control valve and also atits driven side via the control edges 55 and 57, a very reliable andvery sensitive generation of pressure is insured for the pressurechambers of both sides of the transmission.

For the operation of a transmission as illustrated in FIG. I whichpermits the power to be transmitted alternately in either of thedirections of the torque and also in either of the directions ofrotation, that is, a transmission in which the pressure control valvewhich is located at the side of the transmis' sion which then forms itsdriving side is more or less opened it is also possible to employ aslide valve 5b with two control edges as illustrated in FIG. It), thecontrol edges 59 or so of which permits a throttled return flow of theoil to the return line 5ll from the particular side of the transmissionwhich is then the driven side. At the outer sides of the control edges59 and so this slide valve 55 is supplied with oil by two pumps 63 andMl or by one pump with a subsequent flow distributor and through twoseparate pressure lines 61 and 62 each of which is provided for one sideof the transmission.

As illustrated in FIG. I0, conduit 12 leads to the driving side andconduit I3 to the driven side of the transmission. The oil currentleading to the driving side passes through the pressure illl controlvalve 23 at that side, while at the driven side a continuous return flowof oil occurs past the control edge 60 which thus also determines thehydraulic pressure which prevails at the driven side of thetransmission. As already described with reference to FIGS. 8 and 9, itis in this manner possible by means of the slide valve 58 according toFIG. to produce the hydraulic pressures very reliably and sensitivelywhich are required at both sides of the transmission.

Another embodiment of the transmission according to the invention whichdiffers in some respects both structurally as well as in operation fromthe transmission according to FIG. 1 is illustrated in FIG. 11, in whichthose parts which are similar to those in FIG. 1 and have already beendescribed are identified by the same numerals as in FIG. 1. The pistons65 and 66 for the pressure chambers 10 and 11 of the cylinders on disks4 and 6 according to FIG. 11 are in this case designed so as also toform hydraulic cylinders containing pressure chambers 67 and 68 in whichthe hubs 69 and 70 of the axially slidable conical disks 4 and 6 aremovable and serve as pistons for the pressure chambers 67 and 68.

By means ofa pump 71 and a subsequent current distributor 72, oil issupplied under pressure separately through a conduit 73 and a bore 75 inshaft 1 to the pressure chamber 67 and through a conduit 74 and a borein shaft 2 to the pressure chamber 68. From these bores 75 and 76 theoil also passes respectively to pressure control valves 77 and 78 andthence through channels 79 and 80 to the outside. Therefore, bothpressure control valves 77 and 78 of this transmission operatesimultaneously which means that both of them are more or less opened.Both pressure control valves thus provide contact pressures which areresponsive to the load upon the transmission and to its speed ratio. Asalready described with reference to FIG. 1, the contact pressure of theconical disks upon the transmitting element will then be the bestpossible in the hydraulic chamber 10 or 11 either at the driving side orat the driven side of the transmission, while the amount of pressurewhich is still lacking from the best possible contact pressure in thehydraulic chamber at the other side of the transmission must beadditionally produced for which purpose these chambers are respectivelyconnected by conduits 8H and 82 to a distributing slide valve 83 whichis provided with four control edges. This slide valve 83 distributes theoil which is supplied thereto under pressure by a pump 84 to theconduits 81 and 82, while the excessive amounts of oil may flow back tothe suction side of pump 84 via one or the other outer control edge ofslide valve 83 and conduct 85.

For maintaining and varying the speed ratio of the transmission asillustrated in FIG. 11, the same procedure is followed as described withreference to the transmission as shown in FIG. 1. If, after beingadjusted to a certain speed ratio, the transmission according to FIG. 11for any reason tends to change this speed ratio automatically, theresulting movement of the conical disk 4 is transmitted by itsconnection to the control lever 16 which shifts the slide valve 83 insuch a manner that the adjusting movement of the speed ratio which hasbegun will be reversed and slide valve 83 will return to its balancedposition which usually differs from its neutral position. If, however,the speed ratio is to be arbitrarily changed, the necessary actuation ofthe hand lever 18 results at first in a shifting movement of slide valve83 whereby the pressure in chamber 10 and 11 is varied so as to effectthe desired change of the speed ratio. This adjusting operation isstopped as soon as slide valve 83 has again reached its balancedposition which corresponds to the balanced condition of thetransmission.

FIG. 12 finally illustrates a modification of the transmission as shownin FIG. 1 which renders this transmission applicable for use inconnection with a drive unit the power output and speed of which arevariable, for example, the engine of a motor vehicle. Slide valve 14 isfor this purpose connected to a speed governor 86 which, in turn isacted upon by the driving speed by being connected by associated gearteeth 87 to the conical disk 4, and may also be acted upon by theaccelerator 93 of the engine which is connected to the governor by a rod88, a bellcrank 89, a tie rod 90 and a two-armed lever 92 which ispivotably mounted at 91. By means of a bellcrank 94 and a connecting rod95 which is divided into two sections which are axially movable relativeto each other in a certain condition the accelerator 93 acts upon thechoke 96 of the engine.

If the accelerator 93 is depressed from its neutral position, forexample, for accelerating the vehicle, this movement is transmitted bythe flange of a bushing 97 and a compression spring 99 to the flange 98on the shaft of slide valve 14 which is thereby shifted for a smalldistance toward the left of the position as shown and thereby causes thehydraulic pressure to be increased in chamber 11 and reduced in chamber10 so that, as the accelerator 93 is depressed, shaft 2 will run at alower speed and shaft 1 at a higher speed. During this variation of thespeed ratio, the axial movement of slide valve 14 will remain very smallsince, as the speed of shaft 1 increases, the speed of governor 86 willalso increase so that the flyweight members of this governor which alsoact upon flange 98 but against the action of spring 99 will largelyreverse the previous adjustment of slide valve 14 which was effected bythe accelerator 93.

If the accelerator 93 is not further depressed, the transmission will atfirst reach a state of balance and, as the speed of the vehicle thenincreases, it will then be adjusted so that shaft 2 will run at a higherspeed since during the acceleration of the vehicle the enginecontinuously tends to increase its speed which leads through theflyweight members 100 to small shift-- ing movements of slide valve 14toward the right so that the hydraulic pressure increases in chamber 10and decreases in chamber 11. This reverse adjustment is terminated atthe moment when the power input of the transmission is consumed by thedriving resistance of the vehicle so that the vehicle has no longer anytendency to accelerate.

A similar proceeding occurs when the driving resistance increases, forexample, during an uphill drive. At such an increase of the drivingresistance, the vehicle slows down when the output of the engine remainsthe same. Consequently, the speed of both shafts l and 2 decreases andthe compressed spring 99 acting upon the flange 98 then tends to shiftthe slide valve 14 toward the left. This results in a change of thespeed ratio and a reduction in speed of shaft 2 until the power input onshaft 1 is again equal to the power output required so that the vehicleno longer decelerates.

If the engine is to be used to decelerate the vehicle, this has at firstthe result that shaft 2 becomes the driving shaft and shaft 1 the drivenshaft and that the transmitting element 7 therefore exerts a greaterspreading force upon the conical disks 5 and 6 then upon the conicaldisks 3 and 4. However, since chamber 10 still contains at first ahigher hydraulic pressure than chamber 11, the transmission is adjustedto reduce the speed of shaft 1. This adjustment occurs very quicklysince for using the drag of the idling engine the accelerator isreleased which also causes the compression of spring 99 to be reducedwhereby slide valve 14 will be shifted toward the left which furtheraccelerates the above-mentioned adjustment. The transmission is therebyshifted to a speed ratio at which shaft 1 runs at the lowest speed sothat the speed of the engine is also low and its braking effect is verysmall.

For attaining a higher braking effect of the engine, the accelerator 93is designed to be retracted beyond its neutral position as illustrated,whereby a load condition will be simulated onthe governor 86 even thoughthe engine is not affected. This is due to the fact that, when theaccelerator 93 is in its neutral position, the pivot points of tie rod90 on belt crank 89 and on lever 92 are in straight alignment with thepivot point 101 of bellcrank 89 so that any pivoting movement of theaccelerator either toward the right or toward the left from its neutralposition will cause spring 99 to be compressed and slide valve 14 to beshifted toward the left. However, at a pivoting movement of theaccelerator 93 toward the left beyond its neutral position, the device102 will permit the upper section of the connecting rod 95 to shifttoward its lower section so that the position of the choke 96 will notbe affected.

Such a simulated load condition on the governor do therefore also causesslide valve lld to be shifted toward the left of its neutral position sothat the hydraulic pressure will be increased in chamber ill anddecreased in chamber MD with the result that the conical disks 3 and nwill move toward each other and disks 3 and d away from each other. Thespeed of shaft l and thus also of governor as then increases until, dueto the return movement of slide valve lid caused by the action of theflyweiglit members liltl, the transmission has arrived at the speedratio in which the braking power of the engine is applied upon shaft llmaintains the vehicle at a constant speed.

Although our invention has been illustrated and described with referenceto the preferred embodiments thereof, we wish to have it understood thatit is in no way limited to the details of such embodiments but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed our invention, what we claim is:

l. An infinitely variable cone pulley transmission having driving anddriven shafts, at least two pairs, each composed of first and secondconical pulley discs, one pair on each of said shafts, at least oneendless transmitting element connecting and running between said twopairs of conical pulley disks, wherein one disk of each pair on thedriving and driven shafts is movable in the axial direction on its shaftrelative to theother disk and forms a rotating hydraulic cylindercontaining a piston rigidly connected to said shaft, and whereinhydraulic fluid supply means create solely the contact pressures withwhich the conical disks are applied against the transmitting element atboth sides of the transmission in a manner so as to be automaticallyload-responsive, a control element for maintaining and varying the speedratio of the transmission, said movable disks moving axially in responseto variations in torque on the shafts, and a distributing slide valveacted upon by said control element and adapted to distribute thepressure fluid supplied to it from said supply means to the hydrauliccylinders, in which said supply means includes a pressure control valve,and means responsive to a change of the axial position of one of theaxially movable disks for regulating said pressure control valve forcontrolling the hydraulic pressure so as to be load-responsive as wellas responsive to the adjusted speed ratio of the transmission.

2. A transmission as defined in claim I, having a compression springacting on the pressure control valve continuously urging it to closedposition.

3. A transmission as defined in claim ii, in which at least one shaft isprovided with a first channel extending through the shaft substantiallyparallel to its axis forming part of the means for supplying thepressure chamber in the cylinder with hydraulic fluid, and with a secondchannel branching off through a connection from said first channel andleading to the outside; the pressure control valve being mounted in theshaft and adapted to throttle the connection between said two channels;the hub of the axially movable disk having in the wall of its bore atleast one inclined surface, said torqueresponsive means including anintermediate movable element partly projecting radially from the shaftand having an inner end acting through a compression spring upon thecontrol valve, the outer end of said element engaging said inclinedsurface in the wall of the bore, said inclined surface extendingsubstantially parallel to the axis of the shaft, said outer end of theelement being acted upon by said inclined response to the load actingupon this side of the transmission; said inclined surface, for actingupon the pressure control valve in response to the varying speed ratioof the transmission having a varying angularity in its axial direction.

d. A transmission as defined in claim 3, in which said hub has twoinclined surfaces, the outer end of the intermediate element beingdisposed between said surfaces, said inclined surfaces intersecting at aline forming a vertex extending parallel to the axis of the shaft andthe inclined surfaces being disposed at equal angles to each radialplane of the shaft intersecting said vertex.

5. A transmission as defined in claim 3, in which said hub has twoinclined surfaces, the outer end of the intermediate elements beingbetween said surfaces, said inclined surfaces intersecting at a vertexextending parallel to the axis of said shaft, and the surfaces beingdisposed relative to each other at different angles to each radial planeof the shaft intersecting said vertex.

6. A transmission as defined in claim 3, in which the intermediateelement comprises a ball.

7. A transmission as defined in claim 3, in which the slide valve isprovided with four control edges, said fluid supply means include afluid supply line and a fluid return line connected to said slide valve,said slide valve having two annular chambers each connected to one ofsaid cylinders each annular chamber being associated with a pair of saidcontrol edges, the first edge of each said pair being adapted to controlthe supply of fluid to one of said cylinders and the second edge adaptedto control the return flow of fluid to the return line; the two firstedges of both pairs being axially spaced from each other at such adistance that, when the slide valve is in its central position, thefluid supply passages of said valve leading to the two cylinders areequally opened, while the fluid return passages to said return line areclosed by said second control edges; and the axial distance between thefirst and second control edges of one pair which are associated witheach annular chamber being smaller than the axial length of said annularchamber.

ii. A transmission as defined in claim 3, in which the slide valve isprovided with four control edges, said fluid supply means includes afluid supply line and a fluid return line connected to said slide valve,said slide valve having two annular chambers each connected to one ofsaid cylinders; each annular chamber being associated with a pair ofsaid control edges, the first edge of each said pair being adapted tocontrol the supply of fluid to one of said cylinders and the second edgeadapted to control the return flow of fluid to the return line; the twofirst edges of both pairs being axially spaced from each other at such adistance that, when the slide valve is in its central position, thefluid supply passages of said valve leading to the two cylinders areequally opened, while the fluid return passages to said return line areclosed by said second control edges; and the axial distance between thefirst and second control edges of one pair which are associated witheach annular chamber being slightly larger than the axial length of saidan: nular chamber.

9. A transmission as defined in claim 3, in which the slide valve isprovided with two control edges and forms an adjustable flowdistributor.

lltl. A transmission as defined in claim 3, in which said supply meansincludes separate means of equal pressure to supply fluid to each ofsaid cylinders and a return line from each cylinder, one of saidpressure control valves being provided in the supply means to eachcylinder and said slide valve having two control edges and being adaptedto control the return line from the cylinder on the side of thetransmission then forming the driven side thereof.

M. A transmission as defined in claim 3, in which, for producing theload-responsive and speed ratio-responsive contact pressures, eachaxially movable disk has a second pressure chamber connected thereto onthe opposite side of the piston from the first cylinder, a secondhydraulic fluid supply means being provided comprising a source of oilunder pressure and a flow distributor connected thereto; meansconnecting the flow distributor to the second pressure chamber of eachdisk; each second pressure chamber being formed by the piston and a hubon the associated axially movable disk which is axially movable withinthe second cylinder and acts therein as a movable piston; meansconnecting the second pressure chamber through the pressure controlvalve to the outside; the fluid supply means to the first pressurechamber including said slide valve, said slide valve having four controledges; excessive amounts of fluid flowing without pressure past theouter control edges of the slide valve.

12. A transmission as defined in claim 1, in which at least one shaft isprovided with a first channel extending through the shaft substantiallyparallel to its axis forming part of the means for supplying thepressure chamber in the cylinder with pressure fluid, and with a secondchannel branching off through a connection from the first channel andleading to the outside; the pressure control valve being mounted in theshaft and adapted to throttle the connection between said two channels;said torque-responsive means including an intermediate movable elementpartly projecting radially from the shaft and having an inner end actingthrough a compression spring upon the control valve, the hub of themovable disk on said shaft having a recess therein facing the shaft andextending parallel to the axis thereof, a lever in said recess pivotedon said shaft about a radial axis thereof, said lever having an inclinedsurface extending substantially parallel to the axis of the shaft,

the outer end of said element engaging said inclined surface, said outerend being adapted to be acted upon by this inclined surface in responseto the load acting upon this side of the transmission; said lever havinga longitudinal slot extending substantially parallel to the axis of saidshaft; and a pin is secured to and projecting radially inwardly from thewall of said hub into said slot in said lever.

13. A transmission as defined in claim 1, in which the control elementcomprises a two-armed lever one end of which engages into a peripheralgroove in the outer wall of one of the axially movable disks, while itsother end is adjustable.

14. A transmission as defined in claim I, in which the control elementcomprises a speed governor which is rotatable at a speed directlyproportional to the speed of one of the axially movable conical disksand is also adjustable.

1. An infinitely variable cone pulley transmission having driving anddriven shafts, at least two pairs, each composed of first and secondconical pulley discs, one pair on each of said shafts, at least oneendless transmitting element connecting and running between said twopairs of conical pulley disks, wherein one disk of each pair on thedriving and driven shafts is movable in the axial direction on its shaftrelative to the other disk and forms a rotating hydraulic cylindercontaining a piston rigidly connected to said shaft, and whereinhydraulic fluid supply means create solely the contact pressures withwhich the conical disks are applied against the transmitting element atboth sides of the transmission in a manner so as to be automaticallyload-responsive, a control element for maintaining and varying the speedratio of the transmission, said movable disks moving axially in responseto variations in torque on the shafts, and a distributing slide valveacted upon by said control element and adapted to distribute thepressure fluid supplied to it from said supply means to the hydrauliccylinders, in which said supply means includes a pressure control valve,and means responsive to a change of the axial position of one of theaxially movable disks for regulating said pressure control valve forcontrolling the hydraulic pressure so as to be load-responsive as wellas responsive to the adjusted speed ratio of the transmission.
 2. Atransmission as defined in claim l, having a compression spring actingon the pressure control valve continuously urging it to closed position.3. A transmission as defined in claim 1, in which at least one shaft isprovided with a first channel extending through the shaft substantiallyparallel to its axis forming part of the means for supplying thepressure chamber in the cylinder with hydraulic fluid, and with a secondchannel branching off through a connection from said first channel andleading to the outside; the pressure control valve being mounted in theshaft and adapted to throttle the connection between said two channels;the hub of the axially movabLe disk having in the wall of its bore atleast one inclined surface, said torque-responsive means including anintermediate movable element partly projecting radially from the shaftand having an inner end acting through a compression spring upon thecontrol valve, the outer end of said element engaging said inclinedsurface in the wall of the bore, said inclined surface extendingsubstantially parallel to the axis of the shaft, said outer end of theelement being acted upon by said inclined surface in response to theload acting upon this side of the transmission; said inclined surface,for acting upon the pressure control valve in response to the varyingspeed ratio of the transmission having a varying angularity in its axialdirection.
 4. A transmission as defined in claim 3, in which said hubhas two inclined surfaces, the outer end of the intermediate elementbeing disposed between said surfaces, said inclined surfacesintersecting at a line forming a vertex extending parallel to the axisof the shaft and the inclined surfaces being disposed at equal angles toeach radial plane of the shaft intersecting said vertex.
 5. Atransmission as defined in claim 3, in which said hub has two inclinedsurfaces, the outer end of the intermediate elements being between saidsurfaces, said inclined surfaces intersecting at a vertex extendingparallel to the axis of said shaft, and the surfaces being disposedrelative to each other at different angles to each radial plane of theshaft intersecting said vertex.
 6. A transmission as defined in claim 3,in which the intermediate element comprises a ball.
 7. A transmission asdefined in claim 3, in which the slide valve is provided with fourcontrol edges, said fluid supply means includes a fluid supply line anda fluid return line connected to said slide valve, said slide valvehaving two annular chambers each connected to one of said cylinders;each annular chamber being associated with a pair of said control edges,the first edge of each said pair being adapted to control the supply offluid to one of said cylinders and the second edge adapted to controlthe return flow of fluid to the return line; the two first edges of bothpairs being axially spaced from each other at such a distance that, whenthe slide valve is in its central position, the fluid supply passages ofsaid valve leading to the two cylinders are equally opened, while thefluid return passages to said return line are closed by said secondcontrol edges; and the axial distance between the first and secondcontrol edges of one pair which are associated with each annular chamberbeing smaller than the axial length of said annular chamber.
 8. Atransmission as defined in claim 3, in which the slide valve is providedwith four control edges, said fluid supply means includes a fluid supplyline and a fluid return line connected to said slide valve, said slidevalve having two annular chambers each connected to one of saidcylinders; each annular chamber being associated with a pair of saidcontrol edges, the first edge of each said pair being adapted to controlthe supply of fluid to one of said cylinders and the second edge adaptedto control the return flow of fluid to the return line; the two firstedges of both pairs being axially spaced from each other at such adistance that, when the slide valve is in its central position, thefluid supply passages of said valve leading to the two cylinders areequally opened, while the fluid return passages to said return line areclosed by said second control edges; and the axial distance between thefirst and second control edges of one pair which are associated witheach annular chamber being slightly larger than the axial length of saidannular chamber.
 9. A transmission as defined in claim 3, in which theslide valve is provided with two control edges and forms an adjustableflow distributor.
 10. A transmission as defined in claim 3, in whichsaid supply means includes separate means of equal pressure to supPlyfluid to each of said cylinders and a return line from each cylinder,one of said pressure control valves being provided in the supply meansto each cylinder and said slide valve having two control edges and beingadapted to control the return line from the cylinder on the side of thetransmission then forming the driven side thereof.
 11. A transmission asdefined in claim 3, in which, for producing the load-responsive andspeed ratio-responsive contact pressures, each axially movable disk hasa second pressure chamber connected thereto on the opposite side of thepiston from the first cylinder, a second hydraulic fluid supply meansbeing provided comprising a source of oil under pressure and a flowdistributor connected thereto; means connecting the flow distributor tothe second pressure chamber of each disk; each second pressure chamberbeing formed by the piston and a hub on the associated axially movabledisk which is axially movable within the second cylinder and actstherein as a movable piston; means connecting the second pressurechamber through the pressure control valve to the outside; the fluidsupply means to the first pressure chamber including said slide valve,said slide valve having four control edges; excessive amounts of fluidflowing without pressure past the outer control edges of the slidevalve.
 12. A transmission as defined in claim 1, in which at least oneshaft is provided with a first channel extending through the shaftsubstantially parallel to its axis forming part of the means forsupplying the pressure chamber in the cylinder with pressure fluid, andwith a second channel branching off through a connection from the firstchannel and leading to the outside; the pressure control valve beingmounted in the shaft and adapted to throttle the connection between saidtwo channels; said torque-responsive means including an intermediatemovable element partly projecting radially from the shaft and having aninner end acting through a compression spring upon the control valve,the hub of the movable disk on said shaft having a recess therein facingthe shaft and extending parallel to the axis thereof, a lever in saidrecess pivoted on said shaft about a radial axis thereof, said leverhaving an inclined surface extending substantially parallel to the axisof the shaft, the outer end of said element engaging said inclinedsurface, said outer end being adapted to be acted upon by this inclinedsurface in response to the load acting upon this side of thetransmission; said lever having a longitudinal slot extendingsubstantially parallel to the axis of said shaft; and a pin is securedto and projecting radially inwardly from the wall of said hub into saidslot in said lever.
 13. A transmission as defined in claim 1, in whichthe control element comprises a two-armed lever one end of which engagesinto a peripheral groove in the outer wall of one of the axially movabledisks, while its other end is adjustable.
 14. A transmission as definedin claim 1, in which the control element comprises a speed governorwhich is rotatable at a speed directly proportional to the speed of oneof the axially movable conical disks and is also adjustable.